Which transformation of "We couldn't go out because of the bad weather" is correct?

The correct transformation captures the essence of the original statement while also maintaining grammatical correctness and clarity. The phrase "The weather was too bad for us to go out" effectively conveys the reason for not going out, linking the severity of the weather directly to the impossibility of going outside.

This option mirrors the original meaning by indicating that the weather was a barrier to leaving the house. The use of "too bad" emphasizes the extent of the weather's impact, which aligns well with the original implication that the weather was a significant problem.

Other options may lack clarity or do not maintain the same level of grammatical coherence. For instance, they might not effectively communicate the causal relationship between the bad weather and the action of going out. Thus, this transformation stands out as the most effective in retaining the meaning of the original sentence while being syntactically correct.